An increase in multimedia services (e.g., streaming media televisions and video conference services) is an important driving factor for the innovation of broadband technology and standard. Currently, users who view digital video contents via mobile devices are increasing quickly. More and more video applications for mobile services, e.g., Yuku and Sohu, emerge so as to meet these requirements.
This trend leads to difficulties for a content service provider in transmitting media data with a limited bandwidth. Although the bandwidth is always growing stably, the requirement of data communication on the bandwidth grows more quickly. This increase in the requirement is derived from more and more services connected to the Internet and more and more user's requirements on the media content. It was shown by Cisco Visual Network Index (2015) that global mobile data communication was increased by 69% in 2014. In all the mobile data communication, the video data accounted for more than 50% in 2012. Based on the above, it becomes more and more important to increase the multimedia service capability of a mobile communication system and provide a user with high-quality services.
For the flow media, a network condition and a playback condition of the user may change frequently, so an adaptive streaming scheme has been proposed so as to solve the above problem to some extent. A multi-stream video encoder server may encode one video image into streams with different code rates and output the streams. For example, a full-high-definition (FHD) video image (with a resolution of 1920*1080) may be encoded into, and outputted as, a HD stream (with a resolution of 1280*720) and a D1 stream (with a resolution of 720*576) with different resolutions (code rates). A client device may request the video encoder server for a suitable stream in accordance with its network condition, so as to improve the user experience, both for a high-end user and a low-end user.
Such schemes as smooth streaming (Microsoft Corporation), Hyper Text Transport Protocol (HTTP) adaptive streaming (Apple Inc.) and dynamic flash streaming (Adobe Systems Inc.) have achieved great success in market.
Currently, for an adaptive bit rate scheme, it is necessary for a display device at a user side to adjust an input stream, so as to be adapted to the resolution and display an image at the full resolution. A typical amplification algorithm (e.g., a Bicubic algorithm or a Lanczos algorithm (which is used to convert a symmetric matrix into a symmetric tridiagonal matrix through orthogonal similarity transformation, in the name of a twentieth-century Hungarian mathematician Cornelius Lanczos) may introduce a visual error (e.g., sawtooth or annular artifacts). More importantly, the processing is performed by the conventional amplification algorithm based on the received stream, without taking the original multimedia image data into consideration.
Hence, the conventional method for processing the adaptive media service may provide bad user experience.